Device and method for delivering a medicament

ABSTRACT

A device for delivery of medicament is presented that has an elongated housing, a container mounted within the housing and adapted to contain liquid medicament, a stopper slidably arranged within said container, and a delivery mechanism comprising a resilient member, a plunger assembly having one end connected to the stopper and a second end being operably connected to the resilient member, a rotatable latch for releasably retaining the plunger assembly in a first position where the resilient member has an accumulated energy, where rotation of the latch releases the plunger assembly such that the accumulated energy is transferred to the plunger assembly for driving the stopper within the container whereby the medicament within said container is delivered to an injection site. After delivery of the medicament a rotator having a hard stop feature aligns with a rib on the protective shield to prevent retraction of the protective shield.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/116,418, filed Aug. 3, 2016, which is a U.S. National PhaseApplication pursuant to 35 U.S.C. § 371 of International Application No.PCT/EP2015/054365 filed Mar. 3, 2015, which claims priority to U.S.Provisional Patent Application No. 61/948,716, filed Mar. 6, 2014 andSwedish Patent Application No. 1450345-2 filed Mar. 24, 2014. The entiredisclosure contents of these applications are herewith incorporated byreference into the present application.

TECHNICAL FIELD

The present invention relates to a device and method for deliveringmedicament to a patient from a container mounted within the device. Thedevice is adapted to automatically perform the delivery by requiringonly that the user push the device against an injection site. Thedriving force needed for delivery is supplied by a coiled tension springthat is triggered by a rotating latch. A lockout mechanism is providedto prevent retraction of a protective shield after delivery.

BACKGROUND

Devices for the delivery of medicament in an automatic way e.g.auto-injectors, are known as convenient and safe devices for patients toself-administer various drugs themselves. For safety reasons, primarilyto guard against needle sticks, many devices for the delivery of amedicament include covers and other components that protect users beforeand after use of the injector. Although different devices for thedelivery of medicament vary in their total feature sets, they all have amechanism that delivers the contents of a preloaded, prefilled containerautomatically, i.e., without requiring a person to manually force thecontents within a container through a delivery member, e.g., a needle ora nozzle, into the patient.

Auto-injectors are described in U.S. Pat. No. 5,478,316 to Bitdinger etal.; U.S. Pat. No. 7,112,187 to Karlsson; and U.S. Pat. No. 7,125,395 toHommann et al.; U.S. Patent Application Publication No. 2007/0021720 toGuillermo; and International Publication No. WO 2006/057604 by Olson,for example. The automatic delivery mechanism in a device for thedelivery of medicament usually includes a compressed helical compressionspring that drives a plunger rod forward as the spring decompresses uponactivation of the device. In some designs, such springs work well. Afully compressed helical spring provides a force that is large enough toovercome the static friction between the plunger and the inner wall of acontainer, so called break loose force, and the spring at its fullextension, which is often not at its full decompression, provides aforce that is large enough to complete the injection stroke but causingthe probability of the container breakage.

A challenge in the design of such springs is balancing the need forsufficient force at the end of stroke against the need for anot-too-large force during storage (when the spring is fully compressed)that may overload the other components in the device. Such othercomponents may be made of plastics, glass or similar materials that havelimited strengths.

Thus, the drive mechanism in such a device for the delivery ofmedicament should meet the following simultaneous goals: 1) exert enoughforce to overcome the “break loose” force of the container stopper andinitiate delivery of the medication, 2) exert enough force tocomplete—the injection stroke, 3) meet goals 1) and 2) in an acceptabletime frame (usually a few seconds), and 4) exert a low force duringstorage.

Rather than use typical helical compression springs, some deliverydevices use constant force springs or even variable force springs in anattempt to meet the goals mentioned above. For example, in our earlierissued U.S. Pat. No. 8,460,245, such variable force tension springs arediscussed.

Although constant-force or variable springs are better able thancompression helical springs to meet the design goals of injectordevices, there is also a need to provide a smooth and reliable way totrigger the device to initiate the injection process. Visuallyindicating the start of the injection process and showing the progressof the injection are also important in the design of a medicamentdelivery device, such as an auto-injector. Likewise, after the injectionis complete it is important for safety reasons to protect the user andothers by preventing accidental needle sticks. Preferably, the coveringof the used needle should be automatic and nonreversible. In otherwords, the design should not require the user to perform any manualmanipulation of any component of the device, especially componentslocated at the distal or needle end of the device. Our inventionaddresses these concerns while employing a variable force spring as thedriving force to perform the injection.

SUMMARY

One object of the present invention is to provide an automaticmedicament or drug delivery device, which during delivery applies apredetermined sequence of at least two different force profiles to acontainer stopper, which ensures an optimal functionality of the device.This design lowers the risk of damaging the container and/or the deviceduring medicament delivery and reduces the problems with plasticdeformation of the plastic materials of the delivery device incomparison with prior art automatic medicament delivery devices.

Another object is to allow the user to control the manual insertion ofthe needle into the patient's skin while simultaneously pushing a needleshield into the device housing. The retraction of the needle shieldoccurs as the syringe needle penetrates the skin. When a predetermineddepth of needle penetration is achieved, the needle shield retraction iscomplete and the injector is automatically triggered. This is referredto as the “triggering point.” Triggering or firing of the injector isachieved when one or more proximal extending beams on the needle shieldengage cam surfaces on a rotatable latch. The camming action insures asmooth rotation of the latch and avoids the abrupt triggering exhibitedby prior injector designs. The rotation of the latch caused by theengagement of the beams disengages a locking protrusion from an indenton the plunger. As the protrusion moves from the indent into alongitudinal groove on the plunger, the plunger is released to movedistally through the latch without obstruction. An uncoiled tensedplunger spring rewinds forcing a plunger rod to press against thesyringe stopper, which begins the medicament delivery.

The plunger spring is part of the variable force drive mechanism of theinjector and is preferably a variable force spring that can generate apredetermined sequence having at least two different force profiles onlyduring a medicament delivery. Varying the wind, cradling, width orthickness of the band material of the spring or varying the Modulus ofElasticity of the material used to fabricate the spring can impact theforce profiles of the sequence. Selecting the working material indifferent portions or laminating other materials onto a base material indifferent portions, etc. can also achieve this. The predeterminedsequence of the variable force spring comprises a last force profile,which is a profile where the force increases; therefore, the medicamentdelivery device will have an advantage of completely emptying all of themedicament a container or syringe.

The auto-injector of the present invention also contains a visualindication mechanism that reliably and positively provides visibleinformation and feedback to the user that the injection process isprogressing and when it is completed. This visual indication mechanismcomprises a flexible band arranged with different indications, whereinthe band is rolled on a scroll and connected to the plunger on theopposite side of the scroll. When the plunger rod is released from itsnon-delivery state, the flexible band is pulled distally by the movingplunger assembly and indicates the status information to the user by therelated printing on the flexible band.

Yet another object of the invention is the prevention of accidentalneedle sticks, which is achieved through a combination of a retractableneedle shield and a rotator. Longitudinal ribs arranged on an outsidesurface of the needle shield cooperate with grooves arranged on theinner sidewall of the rotator. When the needle shield is pushed into thedevice housing during needle penetration, i.e., retracted, the rotatorwill be twisted or slightly rotated due to the interaction between therib and the groove. After injection, the user removes the device fromthe injection site and the needle shield will fully extend to cover thesyringe needle under the force of a needle shield spring. As the needleshield reaches the fully extended position the rotator again slightlyrotates in the same direction to cause alignment of one or more hardstops located at the distal end of the channels with one or more bearingsurfaces located at the proximal end of the ribs. This alignmentprevents the rib (and the needle shield) from moving axially, thuspreventing retraction of the needle shield and exposure to the usedneedle. The combination of the hard stop and bearing surface of the ribform an irreversible lock of the needle shield.

The above-mentioned objects, along with other objects described below,are accomplished with a delivery device comprising an elongated housing,a container of medicament mounted within the housing having a slidablestopper, and a non-rotating plunger assembly in contact with thestopper. The plunger rod has an indent and a longitudinal groove and isconfigured to move axially relative to the housing from a ready positionand to an end-of-injection position. There is a non-rotating needleshield axially slidable with respect to the housing that has an outersurface comprising a longitudinal rib terminating in a bearing surface,where the needle shield has a proximally extending beam and isconfigured to move from a partially extended position, to a retractedposition and to a fully extended position.

The device also includes a rotator configured as a cylindrical tubehaving an open distal end and a proximal end wall, where the rotator isaxially fixed inside the housing and is rotated through engagement withthe rib to form an irreversible lock to prevent the needle shield frommoving when in the fully extended position. The rotator can also have alongitudinal channel on an inside surface configured to accept axialmovement of the rib. A through hole is provided in the proximal end wallto allow the needle shield beam to pass through to engage the latch. Therotator channel preferably has straight and angled side walls configuredto engage the rib when the rib moves in the proximal direction such thatengagement of the bearing surface of the rib with the angled sidewallimparts a first biasing force that causes the rotator to rotate relativeto the housing to a first position where the flexible tooth partiallyindexes from one ratchet tooth to an adjacent ratchet tooth. Theproximal end wall of the rotator preferably has a set ofcircumferentially arranged ratchet teeth configured to engage a flexibletooth on the latch carrier such that the engagement of the ratchet teethwith the flexible tooth creates a second biasing force urging therotator to rotate from a first to a second position. The partialindexing creates a rotational biasing force that ultimately causes therotator to complete a second slight rotation that aligns the hard stopwith the rib to lock out the needle shield.

The drive mechanism is powered by a coiled spring having a proximaldistal end fixed axially relative to the outer housing and a proximalend attached to the plunger assembly such that the coiled spring is inan extended partially uncoiled tensed configuration having accumulatedenergy when the plunger assembly is in a cocked position. To release thedrive mechanism, i.e., firing the device, a rotatable latch is usedhaving a first position where the latch prevents the plunger assemblyfrom moving axially and a second position where the latch is disengagedfrom the plunger assembly to allow the plunger to axially move distallyrelative to the latch, the rotator and the outer housing such that theaccumulated energy is transferred to the plunger rod for driving theplunger rod and the stopper a predetermined axial distance within thecontainer whereby the medicament within said container is delivered. Thelatch has a cam configured to engage a bearing surface on a proximal endof the needle shield beam. The cam can be configured with a cam anglesuch that proximal axial movement of the beam when engaged with the camcauses a smooth and non-abrupt rotation of the latch to rotate from thefirst position to the second position. The latch preferably has throughhole to accept axial movement of the plunger rod and has an inwardlyprojecting protrusion configured to engage an indent on the plunger rodwhen the latch is in the first position to prevent axial movement ofplunger relative to the housing. The plunger rod can also have alongitudinal groove configured to accept the protrusion when the latchis in the second position, thus allowing unimpeded axial movement of theplunger rod relative to and through the latch.

To allow the user to see the progress of the delivery the proximal endof the housing comprises a window that allows a user to visually observea scrolling tape that moves during the delivery of the medicament. Thedevice also can contain a latch carrier axially fixed to the housing,where the latch is rotatably positioned in the latch carrier and thelatch carrier has a through hole to allow passage of the proximallyextending beam on the needle shield as the needle shield moves in aproximal direction. The needle shield is preferably connected to abiasing element that urges the needle shield to move distally such thata portion of the shield protrudes from the distal end of the housingwhen the plunger assembly is in the ready position. A clicker mechanismgenerates an audible sound during the delivery of the medicament andpreferably comprises a clicker arm on the plunger assembly that engagesteeth on a clicker track that is axially fixed relative the outerhousing.

Using the medicament delivery device described herein, the presentinvention includes a method of performing an injection comprising, incombination, the following steps,

-   -   a) placing a needle shield at an injection site, where the        needle shield is partially extended from a distal end of a        housing of an auto-injector;    -   b) pushing the housing in a distal direction to retract the        needle guard into the housing to a fully retracted position,        where the needle guard has a beam projecting proximally and a        longitudinal rib on an outside surface that engages a channel on        a rotator that is axially fixed to the housing;    -   c) engaging the beam with a rotatable latch when the needle        guard is in the fully retracted position causing the latch to        rotate and unlock a plunger rod;    -   d) coiling a variable force spring attached to the plunger rod        to axially move the plunger rod distally where it engages a        slidable stopper in a container of medicament to deliver the        medicament by injection into the injection site;    -   e) extending the needle shield to a fully extended locked        position when moving the housing proximally from the injection        site and; and    -   f) rotating the rotator to align the rib with a hard stop on the        rotator when the needle shield is in the extended locked        position to prevent retraction of the needle shield into the        housing.

The method can also include the engagement of the rib with the channelto rotate the rotator relative to the housing partially indexing aratchet engagement between the rotator and a rotatably fixed latchcarrier creating a biasing force that results in a second and finalrotation of the rotator when the needle guard is in the fully extendedposition.

According to another aspect of the present invention, the last forceprofile in the sequence is a profile where the force increases. Thevariable force spring is a coil spring of band material and wherein thedifferent force profiles are obtained by suitably adjusting the materialand/or the geometry and/or the natural radius and/or the elastic modulusof the spring. The variable force spring has one end attached to a latchcarrier which is fixedly arranged to the housing and a second end, whichis variably wound, cradled on the proximal end of the plunger.

These and other aspects of the invention and advantages with the presentinvention will become apparent from the following detailed descriptionand from the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described in more detail and with reference tothe appended drawings in which:

FIG. 1 is a perspective view of an embodiment of the medicament deliverydevice according to the invention shown as an auto-injector in the fullyassembled state;

FIG. 2 is a cross-sectional view of the embodiment of FIG. 1 in apartially disassembled state;

FIG. 3 is a perspective exploded view of the embodiment of FIG. 1 in adisassembled state;

FIG. 4 is a perspective view of the needle shield of the embodiment ofFIG. 1;

FIG. 5 is a perspective view of the needle shield, plunger assembly,latch carrier and rotator of the embodiment of FIG. 1

FIG. 6 is a close-up perspective view looking distally of the plungerrod, latching carrier and latch;

FIG. 7 is a close-up perspective view looking proximally of the latchdisassembled from the latch carrier; and

FIG. 8 is a perspective exploded view of the proximal portion of theplunger assembly with the attached tape and spring.

DETAILED DESCRIPTION

In the present application, when the term “distal part/end” is used,this refers to the part/end of the delivery device, or the parts/ends ofthe members thereof, which under use of the delivery device, are locatedthe closest to the medicament delivery site of the patient.Correspondingly, when the term “proximal part/end” is used, this refersto the part/end of the delivery device, or the parts/ends of the membersthereof, which under use of the delivery device, are located thefarthest from the medicament delivery site of the patient. So, forexample, the cap of the reusable auto-injection training devicedescribed herein is located at the distal end of the training injectorand the ribbon window is located at the proximal end. As used herein,the term “container” encompasses all types of medicament containers thatare commercially available that are suitable for injectable liquidcompositions, including prefilled syringes, cartridges and ampoules.

In one embodiment the invention relates to an auto-injection device 1 asbest shown in in FIGS. 1 & 3 comprising a housing or outer body 4 and aremovable cap 2. Cap 2 includes a needle cover remover 2 a that isconfigured to grab and remove rigid cover 2 b and associated flexibleneedle cover 2 c from attachment to the distal end of syringe barrel 10having fixed thereto needle 10 a when the cap 2 is pulled off housing 4.Housing 4 has window or cut-out 5 that allows visual observation of thesyringe barrel 10 and slidable stopper 3 contained within the syringebarrel. As the medicament delivery process progresses a user can watchthe stopper slide axially in the distal direction.

The outer body or housing 4 has a scroll window 6 located at theproximal end where the housing 4 is preferably comprised of an upperbody housing 4 a and a lower housing body 4 b, each preferablycomprising a thermoplastic material. These two body housings can beattached during manufacturing by pins, tongue & groove, snap fit, glue,fasteners, welding or any other known process to provide a secureconnection.

A coiled spring 8 provides the driving force that moves plunger assembly9 distally to move slidable stopper 3 within syringe barrel 10 todispense medicament 10 b from needle 10 a. One end of spring 8, i.e.,the distal end 36, is attached to latch carrier 15 through connectors38. Latch carrier 15 is axially fixed to the lower housing 4 b such thatthere is no relative movement between the latch carrier 15 and thehousing 4. This provides a fixed or anchor position for the distal end36 of plunger spring 8. Because spool 37 that is attached to theproximal end of spring 8 is fixed to the proximal end 9 b of the plungerassembly 9, the spool 37 and attached spring 8 will move relative to thedistal end 36 of the spring and the latch carrier 15 as it rewinds orcoils to a relaxed state. As the plunger assembly 9 is moved proximallyto cock the device during manufacturing, spring 8 is unwound from spool37 and is in an extended state having accumulated energy stored therein.This unspooling or unwinding of the band material used to form spring 8creates a tension or winding force in the plunger spring 8 tending tooppose the proximal setting movement of the plunger assembly duringmanufacturing and assembly of the device. This winding force tends topull the plunger assembly back in the opposite or distal direction inorder to rewind, i.e., coiling, the spring around spool 37. This windingforce is the driving force that allows the plunger rod 9 a to movedistally during medicament delivery or in the case of the auto-injectorembodiment illustrated, perform an injection.

Spring 8 is preferably a variable force spring and is not a traditionalhelical compression spring made from a helix of wire. Spring 8 ispreferably a flat or band spring formed in coil. More preferably spring8 is not a constant-force spring (CFS). With CFSs, force, or load, is afunction of material width, thickness, and coil diameter. The load,which is directly proportional to the material width in a CFS and notdirectly proportional to material thickness, is given by the followingexpression:P=Ebt3 126,4R2  Eq. 1in which P is the load, E is the material's Modulus of Elasticity, b isthe width of the material, t is the thickness of the material, and R, isthe natural radius. If the elastic modulus is given in units of poundsper square inch (psi) and the material width, thickness, and naturalradius are given in inches, then the load is given in pounds (lb). Ofcourse, other systems of units can be used.

As mentioned spring 8 is preferably a variable-force spring (VFS)configured as a coil of band material that exerts a predeterminedsequence of at least two different force profiles. There are three typesof force profiles. A first force profile is a profile where the forcedecreases as the spring relaxes. A second force profile is a profilewhere the force increases as the spring relaxes. A third force profileis a profile where the force is constant as the spring relaxes. As justone of many possible examples, changing the radius of the coil, yieldinga spring that exerts either increasing or decreasing force, isadvantageous in a wide range of products, including devices for deliveryof medicament. Instead of varying the natural radius, i.e., the radiusof the coil, it is possible to make VFSs that exert a predeterminedsequence of at least two different force profiles by modifying the otherparameters in Eq. 1, e.g., the physical shape of the spring. Increasing,either the material's thickness or the width or both. Preferably, theVFS is configured to yield a spring that generates an increasing forceas the spring relaxed, i.e. coils. Varying the width of the materialused to fabricate the VFS produces the desired load profile.

The parameters in Eq. 1 can be manipulated in various ways as necessaryfor the application of the VFS. For example, besides or instead ofvarying the width of the band material, it is possible to vary thematerial's thickness and/or the elastic modulus. The load exerted by aVFS increases more by doubling the thickness than by doubling the width.The elastic modulus in different portions of the material can be variedin many ways, for example by selectively working the material in suchportions, laminating other materials onto a base material in suchportions, etc. A preferred approach is to vary the radius of the coil ofthe spring material. The VFSs used in the present invention areadvantageous to overcome problems due to siliconization profiles of thestopper syringe wall interface, especially at the end of the deliverystroke. The VFSs described here enable the spring forces generated tomatch or compensate the break-loose and glide force profiles within thecontainer generated by different manufacturers and processes better thanconventional compression springs.

Preferably, the plunger spring 8 is composed of spring steel, plasticwith memory, or other material that can be unwound with an applied forceduring manufacturing and assembly of the auto-injector and hasself-rewinding property that uses the stored applied force generatedwhen the device is set to the ready to inject state. As mentioned,preferably the spring has a constant or variable force profile.Preferably, the spring of the present invention has a variable forceprofile comprising a constant force section of about 13 N±10% andvariable force section that provides approximately 17.4 N±10% of force.The springs used in present invention are also known as torsion flatsprings that are typically made of metal because of the minimum amountof deformity and characteristic changes that occur using metal. Thecommon metal used is stainless steal or equivalent metal, which willhave the precise repeatability of the desired force in a very shortdistance uncoiling motion while maintaining its full integrity andcharacteristic as it is repeatedly uncoiled and coiled with a specificconstant torsion force. These types of springs require less space than acompression spring made form a helix of wire and thus can be designedfor placement in the device in very short and tight areas where acompression spring would not fit.

Similar in design to the plunger spring 8 is shield spring 7 as shown inFIGS. 2-3. This spring 7 is used to bias the protective or needle shield13 in a first stand-by position where the distal end 13 a, with attachedshield ring 40, protrudes out of the distal end 4 c of housing 4. Thedistal end 7 a of spring 7 is fixed to housing 4 b and the proximal endor the coil of spring 7 is fixed to a post or protrusion 13 c on theouter surface of shield 13. In a preferred embodiment the shield springs7 comprise two constant force springs. These springs can also bereplaced by another kind of resilient means, e.g., a coil spring, aspiral spring. The wound or coiled ends of the springs are cradledwithin the outwardly annular ledge 13 c and the other end of the springis secured to housing 4.

Protective or needle shield 13 covers or shields the needle from theuser's view and provides user protection from accidental needle sticks,both before and after the injection is completed. Shield 13 isconfigured to slide axially relative to housing 4, but is rotationallyfixed relative the housing. To move the shield 13 from the stand-by orready position to an activate or injection position, the user places theshield ring 40 against an injection site and pushes or moves the housingdistally towards the injection site. This causes the needle shield 13 toslide or retract proximally relative and into the housing 4 untilfingers or beams 29 engage latch 14 (see FIGS. 4 & 7). This engagementof beams 29 with latch 14 occurs through finger through holes 65 and 30located on rotator 60 and on latch carrier 15, respectively. As theshield 13 slides proximally, springs 7 are unwound from the proximalcoil end attached to the shield 13 thus creating a tensioning forcesimilar in nature to the spring force described above in relation to theunwinding of plunger spring 8 when the plunger assembly 9 is set duringthe assembly of the device 1. This tensioning or winding force urgesspring 7 to rewind itself pulling or urging shield 13 in the distaldirection. Once the shield 13 has reached the activate position thedistal end of shield ring 40 becomes approximately flush with the distalend 4 c of housing 4.

In arriving at the activate or triggering position, the needle shieldbeams 29 have a bearing surface 29 a that contacts latch cam 31 on theangled cam surface 31 a in a bearing surface relationship where theangled cam surface slides and rotates relative to the bearing surface 29a at the proximal end of the beam 29. (see FIGS. 4 & 7). Since theneedle shield 13 is rotationally fixed relative to the housing 4, thisbearing contact causes latch 14 to rotate counterclockwise when viewedin the proximal direction as shown in FIG. 7. As shield 13 cannot rotatethe fingers impart a rotating motion of latch 14 relative to latchcarrier 15, which is also rotationally and axially fixed to the housing4. Spring arms 26 on latch 14 engage catches 28 of the proximal insidesurface of latch carrier 15 through spring stops 27 as shown in FIG. 6,as the latch 14 is rotated in the direction shown by the arrow in FIG.6, the spring arms 26 provide a counter biasing or return force thaturges the latch 14 to counter-rotate in the opposite direction. Latch 14has a plunger through hole 14 a that has an inner surface generallymatching the external diameter or shape of plunger rod 9 a. This innersurface has one or more radial extending protrusions or keys 24extending inward and configured to engage plunger rod 9 a in either akey notch or indent 23 or a longitudinal slot or groove 22. When twokeys 24 are used as illustrated in FIG. 7, there will be two notches 23and two slots 22, each preferably diametrically opposed from each other.

When the plunger assembly 9 is pushed back and set to the ready positionduring manufacturing and assembly of the device, notch or indent 23 onplunger rod 9 a slides relative to protrusion 24. Initially theprotrusion 24 is positioned in longitudinal slot or groove 22 on plungerrod 9 a, which allows the plunger rod to move axially relative to thelatch 14 positioned in latch carrier 15. As plunger assembly 9 and notch23 moves proximally during the initial setting of the device, the notch23 will eventually become adjacent to protrusion 24. At that moment,because of the counter rotation force imparted by spring arms 26 thiswill cause the latch protrusion 24 to rotate into notch 23. This notchor indent is positioned longitudinally along the plunger rod 9 a suchthat the latching of the protrusion and the notch 23 occurs when theplunger assembly 9 has reached the fully cocked position. Although inthis cocked position the plunger spring 8 is fully tensioned and urgingthe plunger assembly to move axially in the distal direction, theengagement of protrusion 24 with notch 23 prevents or prohibits axialmovement in either direction. As shown by the direction arrow in FIG. 6,the latch must rotate clockwise (when viewed distally) in order todisengage the protrusions 24 from the notches 23 to drop into and engagegrooves 22. This occurs, as previously described, when fingers 29contact cams 31 and rotate latch 14 in the direction illustrated by thearrow. Rotation of latch 14 is caused because cam 31 has an angledsurface 31 a. Once protrusions 24 rotate into grooves 22 there is nostop or other obstruction in the groove to prevent plunger rod 9 a frommoving distally relative to latch 14, protrusion 24, and latch carrier15.

Another feature of the present invention is rotator 60 as bestillustrated in FIGS. 2 and 5. The rotator 60 provides a safety featureto the device in that at the end of the delivery or injection sequenceor process the rotator moves (rotates) relative to the housing 4 suchthat the needle shield 13 is irreversibly locked in a fully extendedposition covering the used needle. The rotator provides a hard stop 64as explained below that prevents the needle shield from retractingproximally into the housing. As such, the user and others are protectedagainst accidental needle sticks. Referring to FIG. 4, one or more ribs51 are located on the outside surface of needle shield 13 that terminatein a bearing surface 51 a. Preferably these ribs are integral to theshield and are formed during the molding process used to fabricateshield 13. As the needle shield is pushed into the housing during theinjection process, the bearing surface 51 a first engages sidewall 62 aand then engages angle sidewall or ramp 63. (see FIG. 5). Because theneedle shield is rotatably fixed with respect to the housing it cannotturn so therefore the interaction of bearing surface 51 a with ramp 63causes the rotator 60 to rotate slightly in the direction shown by thearrow 70. With the bearing surface 51 a in channel 61 and the rotatornow stationary, the needle shield rib 51 continues to travel alongsidewall 62 b as shield 13 is further pushed or retracted into housing 4moving proximally. Eventually, fingers or beams 29 will pass through athrough hole 65 in the proximal end wall 68 of rotator 60. Preferablythere are two through holes 65 that align with two fingers 29. Whenfingers 29 contact latch 14 causing it to rotate, the piston rod 9 awill move distally to complete the medicament delivery. When the userremoves needle shield 13 from the injection site, the needle shieldreverses direction and starts to extend from the housing moving distallycarrying ribs 51 along channel 61 in the reverse direction. When thebearing surface 51 a arrives at a point just outside of the distal endof channel 61 the needle shield is fully extended and covers the usedneedle. The bearing surface 51 a is just outside of channel 61 allowingrotator 60 to further slightly rotate in the same direction as the firstslight rotation such that the bearing surface 51 a becomes aligned withhard stop 54 located at the terminal or distal end of channel 61. If theneedle shield were to be pushed proximally in an attempt to retract theshield into the housing the bearing surface 51 a would engage hard stop64 and prevent any axial or retracting movement of the shield. Inessence the combination of the bearing surface 51 a and hard stop 64forms an irreversibly lock against retraction.

The rotator essentially makes two small rotations during the medicamentdelivery process from start to end. Biasing forces are needed to causeboth rotations. The first rotation results from the biasing forceimparted by the bearing surface 51 a contacting angled sidewall 63. Asthe rotator is forced to rotate, ratchet teeth 66 that are arrangedcircumferentially around a through hole that allows passage of plungerrod 9 a, move out of engagement with one or more flexible teeth 67located on a distally projecting extension of latch carrier 15. Thisfirst rotation of the rotator is not large enough to fully index theflexible tooth 67 into an adjacent ratchet tooth. This less than fullindexing, i.e., partial indexing, imparts a second biasing force on therotator as a result of the flexible tooth urging the rotator to continuein rotation in the direction of the first slight rotation caused by thefirst biasing force imparted by rib 51. This second biasing forceremains as ribs 51 travels proximally and then distally in channel 61.When rib 51 disengages from channel 61 when the needle shield is allowedto fully extend out of the housing, the second biasing force causes therotator to complete the second slight rotation such that the hard stop64 becomes in axially alignment with bearing surface 51 a. This secondrotation of the rotator completes the formation of the irreversiblelockout of the needle shield 13.

As stated, plunger spring 8 provides the driving force to move plungerassembly 9 axially in the distal direction when the medicament deliverydevice is fired or triggered by the user. No trigger button or switch isrequired to fire device 1 and, as such, there is no mechanism in thedevice that requires manipulation using the user's fingers to push,flip, de-latch, or otherwise activate in order to fire the device. Allthat is required to trigger the injection procedure is to press theshield 13 against an injection site.

The medicament container or pre-filled syringe 10 as illustrated in FIG.3 is positioned in and held axially fixed by carrier 11. Carrier 11 isrequired because it provides an additional housing component for thesyringe as well as an axial alignment feature for the syringe shield.The carrier also allows the medicament container to be held in aposition where the container will have minimum rotation and or movementas a result of the activation or deactivation phases and repeatedactions by a user. A syringe collar 55 is disposed between the syringefinger flanges 56 and carrier 11. (see FIG. 2). This collar provides adamping force or cushioning effect between the syringe and the carrierto avoid breakage of the syringe or the delivery device. The collar ispreferably fabricated of a thermoplastic elastomer (TPE) or some othersoft plastic that can absorb medicament delivery forces generated byspring 8.

The medicament delivery device of our invention also generates anaudible noise or signal to the user as the injection proceeds from thestart to the end. This audible feature is achieved preferably by the useof a clicker track 17 fixed to the housing 4 b and engaged by a flexibleclicker arm 21 attached to plunger assembly 9. As illustrated in FIGS. 3& 8, a preferred configuration uses two clicker arms 21 and two clickertracks 17 diametrically opposed to each other. One clicker track isaxially fixed and parallel to the longitudinal axis of the insidesurface of housing 4 b and the other clicker track is similarly axiallyfixed to the inside surface of housing 4 a. One clicker arm 21 islocated on the top portion of plunger assembly 9 as shown in FIG. 8 andthe other clicker arm (not visible) is located on the underside orbottom of the proximal end 9 b of plunger assembly 9 to engage theclicker track 17 shown in FIG. 8. As the plunger assembly moves distallyduring the injection process, the clicker arm engages the clicker trackand rides up and over the teeth positioned longitudinally along thetrack 17 causing a “clicking” sound that is heard by the user. The teethseparation and configuration is selected such that each click preferablymatches the delivery of a unit dose of the medicament from thepre-filled container. The design of the clicker arm 21 and clicker track17 must take into account the setting of the device during assembly and,as such, must allow the plunger assembly to move in the oppositeproximal direction during setting. In other words, the engagement of theclicker arm and clicker track must not be unidirectional, but insteadmust be bidirectional. Another feature of the clicker is that once thenoise stops the user will know that the injection is complete or thatthe device has been fully set during assembly. Alternatively, theclicker track can have larger or different shaped teeth or a tooth atthe distal end such that as the plunger assembly finishes movingdistally the clicker arm will engage the larger/different tooth and makea louder or different noise signifying the end of the injection process.

The scroll window 6 located at the proximal end of housing 4 allows theuser to watch a moving scroll of tape 33 unwind as the injectionprocedure is in progress. The window can be comprised of any clear,transparent or translucent material that will allow the user to seemovement of tape 33. Preferably the window is constructed or formed as alens to magnify the appearance of tape 33. The observation of the movingtape 33 provides a visual signal to the user of when injection begins,as it progresses, and when the injection ends. The progress scroll ortape 33 is mounted on scroll spindle 20 as illustrated in FIG. 2.Preferably, the tape 33 contains indicia 34 that provide the user with avisual signal through window 6 that the tape is moving in the directionof the arrow in FIG. 8 as the injection progresses.

Spindle 20 is fixed to lower housing 4 b and is prevented from movingaxially, but is allowed to rotate about the stationary fixed axialposition. The end of the tape opposite spindle 20 is fixed or attachedto plunger assembly 9 and moves axially in the distal direction as shownby the arrow in FIG. 8 during activation of the delivery or injectionprocess. As the plunger assembly 9 moves distally it pulls tape 33 inthe direction of the arrow thus unwinding the tape from spindle 20 andpreferably revealing indicia 34, which in turn shows the user movementof the tape signaling that the injection process is progressing. At thecompletion of the injection sequence when the plunger assembly 9 hastraveled to its terminal or final distal position, the tape 33 has beenunwound from spindle 20 but remains connected to the spindle.

Preferably tape 33 is composed of a material that is resilient and hasmemory, like spring steel or a plastic composite with memory, such thatas the plunger assembly 35 is set during manufacturing and assembly ofthe device, the tape will wind onto the spindle to the startingposition. This winding process is analogous to that used in hand heldtape measures that have automatic rewind features. Alternatively, thespindle may be connected to a biasing assembly or component, such as aspring, such that the biasing component is stressed or tensioned as thetape is unwound. During the initial setting of the plunger assembly sucha biasing component causes the spindle to reverse rotation direction andwinds the tape to the starting position.

It is to be understood that the embodiments described above and in thedrawings are to be regarded only as non-limiting examples of theinvention and that they may be modified in many ways within the scope ofthe claims. This application is therefore intended to cover anyvariations, uses or adaptations of the invention using its generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

The invention claimed is:
 1. A device for the delivery of medicament, comprising: an elongated housing having a proximal end and a distal end; a plunger assembly axially movable relative to the housing, where the plunger assembly comprises a proximal end and a distal end; a needle shield rotationally fixed and axially slidable with respect to the housing and comprising at least one bearing surface, where the needle shield moves from a first position to a triggering position to a second position; a rotator axially fixed relative to the housing that is rotated relative to the housing when the bearing surface of the needle shield moves proximally through holes in the rotator, where the rotator moves to form a lock that prevents the needle shield from moving distally after the needle shield has moved from the triggering position to the second position; and a latch axially fixed to relative to the housing and rotatable relative to both the housing and the rotator when the needle shield moves from the first position to the triggering position.
 2. The device of claim 1 where the latch has a first position where the latch prevents the plunger assembly from moving axially and a second position where the latch is disengaged from the plunger assembly to allow the plunger to move axially.
 3. The device of claim 1 further comprising a spring having a one end fixed axially relative to the housing and a second end attached to the plunger assembly where the spring is under tension having an accumulated energy when the plunger assembly is in a cocked position and the needle shield is in the triggering position.
 4. The delivery device of claim 1 wherein the needle shield further comprises an outer surface having a longitudinal rib terminating in a bearing surface, where the longitudinal rib moves within a channel on an inside surface of the rotator causing the rotator to rotate as the needle shield moves from the first position to the triggering position.
 5. The device of claim 1 where the needle shield is connected to a biasing element that urges the needle shield to move distally when the needle shield is in the triggering position such that when the needle shield moves from the triggering position to the second position a portion of the needle shield protrudes from the distal end of the housing.
 6. The device of claim 1 further comprising a latch carrier axially fixed to the housing, where the latch is rotatably position in the latch carrier.
 7. The device of claim 6 wherein the latch carrier comprises a passageway that is configured to allow the at least one bearing surface of the needle shield to move axially relative to latch carrier as the needle shield moves in a proximal direction.
 8. The delivery device of claim 7 wherein the at least one bearing surface is located on a terminal proximal end of a proximally extending beam.
 9. The device of claim 1 wherein the housing further comprises a clicker mechanism that generates an audible sound during the delivery of the medicament.
 10. A device for the delivery of medicament, comprising: an elongated housing having a proximal end and a distal end; a plunger assembly axially movable relative to the housing, where the plunger assembly comprises a proximal end and a distal end; a clicker mechanism that generates an audible sound during the delivery of the medicament, a needle shield rotationally fixed and axially slidable with respect to the housing and comprising at least one bearing surface, where the needle shield moves from a first position to a triggering position to a second position; a latch carrier axially fixed relative to the housing comprising a latch that is rotatable relative to the housing and to the latch carrier when the needle shield moves from the first position to the triggering position; and a spring having a proximal end attached to the plunger assembly and a distal end attached to the latch carrier and axially fixed relative to the housing.
 11. The device of claim 10 where the clicker mechanism comprises a clicker arm on the plunger assembly and a clicker track axially fixed relative to the housing.
 12. The device of claim 11 where the clicker track comprises a plurality of teeth positioned longitudinally along the clicker track.
 13. The device of claim 12 where the clicker arm engages the clicker track and rides up and over the teeth to generate a user audible “clicking” sound.
 14. The device of claim 12 where the teeth separation and configuration is selected such that each user audible “click” corresponds to a delivery of a unit dose of the medicament from a pre-filled container in the housing.
 15. The device of claim 11 where the clicker arm moves proximally and distally relative to the clicker track.
 16. The device of claim 10 where the where the clicker mechanism comprises a first and a second clicker track and a first and a second clicker arm.
 17. The device of claim 10 where the clicker mechanism generates a different audible sound when the delivery of the medicament is complete.
 18. The device of claim 17 where the audible sound during delivery of the medicament is a result of a clicker arm engaging and moving axially relative to a stationary clicker track where the clicker arm rides up and over a set of teeth having a first size or shape and the different audible sound is caused by the clicker arm engaging a tooth having a second size or shape.
 19. The device of claim 10 wherein the latch carrier comprises a passageway that is configured to allow a portion of the needle shield to move axially relative to latch carrier as the needle shield moves in a proximal direction from the first position to the triggering position.
 20. The device of claim 19 wherein the portion of the needle shield that passes through the through hole of the latch carrier comprises a proximally extending beam. 